Field of the Invention
The present invention relates to a surge-protection circuit, and in particular to an on-chip surge-protection circuit and an on-chip surge protection method.
Description of the Related Art
Damage caused by surge or electrostatic discharge (ESD) has become one of the main reliability concerns with integrated circuits (IC) products. FIG. 1 is a schematic diagram of a conventional digital subscriber loop system 100. The digital subscriber loop system 100 includes a primary surge protection component 110, a transformer 120, a secondary surge-protection component 130, a loop component 150 and logic components 160A and 160B. Nodes TXN, TXP, RXP and RXN are the IC pins. When surge occurs near the loop component 150, the primary surge-protection component 110 and the secondary surge-protection component 130 will release the abrupt discharging and protect the digital subscriber loop system 100 and the IC.
However, the primary surge-protection component 110, the secondary surge-protection component 130 and/or other protection components (such as Zener diodes or a Thyristor Surge Suppresser) are equipped on the system board of the digital subscriber loop system 100, costing more and taking up space. Therefore, an on-chip surge-protection circuit embedded within the IC is needed to reduce cost and also to simplify the structure of the digital subscriber loop system 100.